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421 Error when sending email IP address is not permitted to send messages

Frequent Visitor

421 Error when sending email IP address is not permitted to send messages

Hi, I have 3 email programs (Windows Live Mail, Outlook, and Mail Bird) and just in the last 2 days, none of them can send Outgoing messages (Incoming emails are fine).  I've already talked to support and received no assistance.  Here's the error message.

 

An unknown error has occured.  Server Error 421  Server Response:  421 resomta-po-17v.sys.comcast.net

resomta-po-17v.sys.comcast.net CSI IP xxx.xxx.xx.xxx (with the actual numbers of course) is not permitted to send messages.

Please contact support if you feel this is in error.

Server: 'smtp.comcast.net' 

Windows Live Mail Error ID: 0x800CCC67

 

That IP address is NOT any of my devices...not my smartphone or computer...does anyone have an idea what I can do?  Thanks

 

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

I'm having exactly the same problem.  Just started earlier this week.  None of my sent mails have gone out.  The web portal works fine.  I suspect that the IP address is my router address, and it is being blocked by Comcast for some reason, but the support person I chatted with insisted that it was my email software configuration, not their server, since the webmail works. 

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

Thank you for confirming that I'm not crazy...I have other computers with the same software configuration that have no problem.  It's only this one IP Address that Comcast is blocking...I'm going to keep calling Tech Support until I get someone with the knowledge of what's going on...if you finally get an answer, please let me know what it was!  Thanks!

 

Oh, you can open up a Command Prompt window and type in    ipconfig    then press the Enter key...that should give you the IP Address of your router...in my case, it's not that IP Address that they're blocking...

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

Thanks, I did verify that it is my IP address that they are blocking.  I'm going to see if my VPN will let me get around it, but I would like to hear from Comcast why they are doing it.

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

Oops, the Command Prompt Ipconfig command will only give you your Local IP Address, NOT the Public IP Address which is what Comcast is blocking.  For that, go to:

 

https://www.whatismyip.com/

and you'll get your Public IP Address.  That IP Address will match what Comcast is blocking.

Expert

Re: 421 Error when sending email IP address is not permitted to send messages


@Mikeprofla1 wrote:

 

Oh, you can open up a Command Prompt window and type in    ipconfig    then press the Enter key...that should give you the IP Address of your router...in my case, it's not that IP Address that they're blocking...


FWIW, that output gives the private / non-routable LAN interface IP address that the router's DHCP server is assigning to the particular network clients and not the public / routable WAN IP interface address that the Comcast DHCP is assigning to the router / connection.

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I realized that after I typed it..you used much more eloquent language than I did to explain it better...thanks...I'm 61 years old and don't remember all the technical terms any more!  HA!

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

I tried to bypass by using VPN software but the SMTP server still sees the non-routable IP. 

The problem still remains, why is my IP address being blocked by Comcast, and how do I get it fixed?

Expert

Re: 421 Error when sending email IP address is not permitted to send messages

 .@

 

Smiley Happy

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

Vthatcher, have you solved your situation yet OR has it gotten WORSE like mine has...now I can't SEND or RECEIVE emails on any of my local POP3 based email programs...

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

What I've figured out is that Comcast is blocking outgoing emails from the IP address coming from my Verizon router.  I was able to verify that by sending emails from my office computer this morning, which, of course, has a different IP address.

Comcast tech support was supposed to kick my problem up to the next level, but I'm not holding my breath waiting for them to get back to me.  I'm not a current Comcast customer, Comcast is "supporting" previous customers' Comcast email addresses.  I can't help wondering if this is their way of getting rid of me.

I called Verizon this morning about changing my IP address and told that doing a hard reset (red button on back of router) would recycle the DHCP and give me a new IP address.  I will do that when I get home tonight.

Long-term solution is obviously to move to a new email provider, but I need to get back to a functional email first.

Good luck!

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I'm in the same boat - former Comcast customer who was forced to go to Spectrum here in NC when I moved from S. Florida...kept my 4 Comcast email addresses...I too will try to hard reset my modem / router to see what happens...thanks for the thought...

Official Employee

Re: 421 Error when sending email IP address is not permitted to send messages

If you've been unable to resolve the issue thus far, please send me a PM with the error message that you're getting (including the IP).  I'll do my best to get the situation rectified.  To send a PM, click on my name, and then look for a link that says "Private Message".

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

Don't know if it's the same issue or not, as I don't get an error message, but my sent emails from the comcast webpage are not being received.  Just the last 2-3 days.

New Poster

Re: 421 Error when sending email IP address is not permitted to send messages

I resolved the issue.  Doing a reset of the router did not change my IP address, as it should have, so I replaced the router at Verizon's suggestion.  Problem solved.

If you have a router that is functioning correctly resetting it should resolve the problem.

Just an FYI, a temporary work-around was to use my Iphone as a Wifi hotspot allowed me to use the Comcast email while I was sorting the router issue.

Good luck to everyone else.

Regular Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I am having the same problem.  My emails won't send from my Outlook Account although I receive them as usual.  This started Wednesday morning, May 16th.  I've been on the phone countless hours with both Microsoft and Comcast.  My error messages say Sending' reported error (0x800CCC67):' The server responded: 421 resomta-ch2-03v.sys.comcast.net (My IP address) is not permitted to send messages.  Please contact support if you think this is in error.

 

I do have internet service with Frontier but have been paying Comcast separately for the continued use of my comcast email address.

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I have the same exact message please attached.

I've been a Comcast customer for over 20 years, however I had to move to my work ISP, 

I kept comcast emails, I'm able to recieve emails but I can't send, using 2010 Outlook.

I didn't change any thing, tried all the suggested ports, tried Imap and pop.

I can however send emails using Comcast web site.

please help

AK

Regular Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I have been having the same problem for a couple of weeks now: An error occurred while sending mail: The mail server sent an incorrect greeting: resomta-ch2-09v.sys.comcast.net resomta-ch2-09v.sys.comcast.net CSI IP xxx.xxx.xxx.xxx is not permitted to send messages. Please contact support if you feel this is in error.. I have contacted Comcast a couple of times and they have escalated the problem a couple of times. A couple of days after the escalation, the problem is solved for some brief period of time and then it re-occurs. The IP address that is not permitted to send messages is different in each episode since I am using a VPN. The problem still exists with the VPN turned off, however. Rebooting the router, turning antivirus off, etc. does not resolve the problem.
Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I'm the original poster that started this thread...I'm using a Motorola Surfboard SBG6700-AC modem / router - I'm curious, is anyone else using a Motorola modem / router or some other brand?  Thanks...

Regular Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I'm using the Arris modem supplied by Comcast and the Surfboard SB6141 as my router.

Regular Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

On further testing, I believe that my version of this problem is affected by my VPN.  I use a VPN client that has a "disconnect" and a separate "exit" button.  I thought I was turning the VPN off when I "disconnected" (in this case, I would still get the error message when I tried to send an email).  When I "exit", I do not get the error message and can send email.  I am doing further testing by uninstalling the VPN on one computer and leaving it installed on another to see what I get.  It makes some sense to me that Comcast may be blocking the IP addresses of the VPN servers and, by disabling the VPN, I no longer run afoul of their blocker.

Official Employee

Re: 421 Error when sending email IP address is not permitted to send messages

 

Hi Anon859605, I replied to your original post regarding this issue. Please reach back out to me there for further assistance.

 

 

@aluminum and @Mikeprofla1, if you need additional assistance in getting this error cleared up please send me a private message with your full name, street address, and account number by clicking on my name (ComcastAmir) and then "private message me" and I can check your settings in our back end system. 

Regular Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I believe I have tracked part of my problem to my VPN provider - Private Internet Access.  They reported to me that they have started a whitelist of smtp providers.  What I don't understand (and I am waiting for a response from them) is that they want the IP address of smtp.comcast.net so that they can add it to their whitelist.  Unless I misunderstand, they can get this themselves with a ping. 

With my VPN disconnected (not just 'exited'), I have no problem sending email to either of my SMTP services (comcast and aplus). 

Can someone from Comcast talk with the PIA people?  It's not like Comcast and PIA are mom-and-pop corner stores.  This has got to be a problem for a lot more folks than just me.  PIA says that they have arrangements with other providers of email services to allow SMTP from their servers including AOL, Gmail, Outlook, and Yahoo.  They (PIA) want to block spammers and apparently those other email providers are actively doing something about spammers.  It is not clear to me why Comcast is not included in that group.

 

 

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

I replied back with all your suggestions as i noted on my previews respond, I still can't send mail from my Outlook.

please help

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

As of now I still can't send emails using my Outlook, I've done everything I was asked to do by you (Comcast Employee).

so far no resoults, It is very frustrating since I'm "not a customer" any more, after being a customer foir 25 years I was hoping for some moreattempt on your part.

Any help ? Any?

AK

Frequent Visitor

Re: 421 Error when sending email IP address is not permitted to send messages

Anon, my problem was finally solved by a knowledgeable Comcast rep on this board...I too am no longer a Comcast customer (which appears to be the source of this problem).  Comcast recently migrated some systems over to new platforms and since my old account number was no longer compatible / valid, I got kicked out of the system.  Once he reset my account, the problem has been fixed!  Hope this helps you...